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Search: id:A060517
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| A060517 |
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Triangle T(n,k) of series-reduced (or homeomorphically irreducible) graphs with loops on n labeled nodes and with k edges, k=0..binomial(n+1,2). |
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+0
2
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| 1, 1, 0, 1, 1, 2, 1, 1, 3, 6, 6, 6, 3, 1, 1, 6, 15, 34, 58, 60, 60, 50, 33, 10, 1, 1, 10, 35, 120, 265, 475, 820, 1200, 1615, 1860, 1693, 1060, 425, 105, 15, 1, 1, 15, 75, 330, 990, 2691, 6326, 13170, 26205, 48055, 79206, 112863, 133535, 124680, 88890, 47874
(list; graph; listen)
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OFFSET
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0,6
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REFERENCES
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I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley and Sons, N.Y., 1983.
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FORMULA
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E.g.f.: (1 + x * y)^( - 1/2) * exp( - x * y/2 - x^2 * y^2/4) * Sum_{k=0..inf}(1 + x)^binomial(k + 1, 2) * exp( - x^2 * y * k^2/(2 * (1 + x * y)) + x^2 * y * k/2) * x^k/k!
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EXAMPLE
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[1], [1, 0], [1, 1, 2, 1], [1, 3, 6, 6, 6, 3, 1], [1, 6, 15, 34, 58, 60, 60, 50, 33, 10, 1], [1, 10, 35, 120, 265, 475, 820, 1200, 1615, 1860, 1693, 1060, 425, 105, 15, 1], [1, 15, 75, 330, 990, 2691, 6326, 13170, 26205, 48055, 79206, 112863, 133535, 124680, 88890, 47874, 19443, 5925, 1330, 210, 21, 1], ...
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CROSSREFS
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Row sums: A060516, A003514, A060514.
Sequence in context: A056646 A056056 A136462 this_sequence A074662 A025243 A135701
Adjacent sequences: A060514 A060515 A060516 this_sequence A060518 A060519 A060520
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Mar 24 2001
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